Hydroxyethyl-beta-(3,5-di-t-butyl-4-hydroxy benzylthio) alkanoate



United States Patent 3,504,012 HYDROXYETHYL-fl (3,5-DI-T-BUTYL-4-HYDROXY I BENZYLTHIO) ALKANOATE Harry lit-ans, Springdale, and Jay R. Woltermann, Cincinnati, Ohio, assignors to National Distillers and Qhemical Corporation, New York, N.Y., a corporation of Virginia No Drawing. Filed Apr. 7, 1967, Ser. No. 629,121 Int. Cl. C07c 143/52 US. Cl. 260470 2 Claims ABSTRACT OF THE DISCLOSURE Organic materials can be stabilized with a compound having the formula n is a positive integer between 1 and 8; m is a positive integer between 2 and 10; n and m may be equal to each other or not; and. v

0 l D--OH, OR, or O -R where R is an alkyl group having from 1 to 22 carbon atoms.

This inventioii'relate's to novel compounds and to their use as stabilizers for organic materials. More particularly, this invention is concerned with the use of these compounds as" stabilizers and antioxidants for olefin polymers and to the polymer compositions stabilized therewith.

A rapidly expanding industry utilizing polyolefin resins has created a need for stabilizers that will render the finished articles of manufacture more useful, more versatile in application, and more nearly permanent. Polymers of aliphatic olefins have a combination of properties, such as high resistance to stress cracking, high tensile strength, and stability under load, that makes themuseful in the manufacture of pipe, film, wire, coatings, or various molded objects such as bottles andthe like.

These polyolefins, however, are subject to considerable degradation at the high temperatures that are required in their processing or that may be encountered by the finished articles. They may also be degraded by chain cleavage resulting from oxidation or attack by acids. The molecular breakdown which occurs inthese polymers during fabrication is usually evidenced by increased brittleness at low temperature and reduced tensile strength and dielectric properties.

It is customary to incorporate small amounts of stabilizers into the polymer to improve the resistance thereof to thermal and oxidative degradation, such as various 3,504,012 Patented Mar. 31, 1970 ing into the polymer composition a small amount of a compound having the generic formula n is a positive integer between 1 and 8; m is a positive integer between 2 and 10; n and in may be equal to each other or not; and

0 D=OH, OR, or Oi J-R where R is an alkyl radical having from 1 to 22 carbon atoms which may be straight chain or branched.

The resulting stabilized compositions can be processed under conditions of elevated temperature and mechanical working without substantial increase in the melt flow rate and without important color change.

Specific examples of the stabilizers of this invention include such compounds as hydroxyethy1-[3-(3,5-di-t-butyl- 4-hydroxybenzylthio) propionate having the formula hyd'roxypropyl B (3,5-di-t-butyl-4-hydroxybenzylthio) propionate and hydroxybutyl-[i-(3,5-di-t-butyl-4-hydroxybenzyltrio) propionate.

Although this invention will be described with regard to the use of the novel compounds as stabilizers for polyolefins, it is to be understood that the compounds are suitable also as stabilizers for other materials, such as elastomers, including both natural and synthetic rubbers; synthetic resins, e.g., vinyl resins, polystyrene, polyamides, polyacetals, and polyesters; fats; gasolines; waxes; soaps;

oils; greases; and so forth.

The materials with which this invention will be illustrated are the normally solid homopolymers and copolymers of aliphatic olefins having from 2 to 8 carbon atoms per molecule, such as ethylene, propylene, l-butene, isobutylene, 2-butene, l-pentene, and l-hexene, and mixtures amines, diaryl sulfides, phenolic compounds, organic phosthereof.

In general, the amount of agent to be added to the polyolefin depends upon the degree and kind of stabilization desired. The amount of antioxidant can vary from about 0.001 to about 5.0 percent, based on the weight of the polyolefin, with amounts of approximately 0.05 to 0.5 percent being preferred.

As a rule, it is preferred to use the minimum amount required to achieve the desired results.

The compounds of this invention can be mixed with the polyolefin in any suitable manner that will effect thorough distribution and dispersion. This can be accomplished in equipment suitable for mixing solids, as by milling the polyolefin with the additive on heated rolls such as are used in the compounding of rubber or on other suitable milling or mixing equipment, such as for example a Banbury mixer or conventional rubber mill. Instead of adding the stabilizing agent to the polymer in the solid or molten state, it can be added to a solution or suspension of polymer in an organic solvent or to an aqueous dispersion thereof and the volatile solvent subsequently removed by vaporization.

The antioxidants of this invention may be supplemented by small amounts of finely dispersed particles of carbon black to shield thepolyolefin from the deleterious degradative effects of ultraviolet radiation, thereby improving its resistance to light deterioration. Carbon black suitable for use herein includes both activated and unactivated types, such as channel carbon black, furnace carbon black, animal or vegetable carbon black, thermal carbon black, light lamp blacks, acetylene blacks, and the like,-and carbon blacks activated in the presence of such materials as oxygen, sulfur, or selenium. The average particle size of carbon black used herein should be below about 1000 angstroms and preferably below about 200 angstroms, so as to ensure a uniform dispersion of the carbon black through the polymer. Amounts of carbon black within the range of about 0.5 to 5.0 percent by weight of the polymer, and preferably about 0.1 to 3.0 percent, are satisfactory. For some polyethylene applications, carbon black concentrations of up to about 50 percent by weight can be present, especially where partially conductive polyethylene-carbon black compounds are employed.

The preparation of the novel stabilizers and their use in polyolefin resin compositions are illustrated by the examples which follow. It is to be understood, however, that these examples are given solely for the purpose of illustration and that the invention is not to be regarded as being limited to any of the specific materials or conditions recited therein except as set forth in the appended claims.

EXAMPLE I 9.2 grams of sodium (0.4 atom) was dissolved in 20 ml. of ethanol in a 500 ml. Erlenmeyer flask equipped with a reflux condenser. When the solution was complete, the flask was cooled to C. and 60.1 grams of hydroxyethyl mercaptopropionate (0.4 mole) was quickly added. The contents, sodium mercaptide, were placed in a dropping funnel.

Into a S-necked, 3-liter Morton flask equipped with a stirrer, N inlet, thermometer, reflux condenser and dropping funnel was weighed 101.9 grams of the 3,5-di-t-butyl- 4-hydroxy :benzyl chloride (0.4 mole), prepared by the method disclosed by N. P. Neureiter in J. Org. Chem. 28, 3486-90 (1963), dissolved in about 100 ml. of ethanol. The flask was heated to 60 C. and the sodium mercaptide was added dropwise at a fairly rapid rate. Stirring was continued for about one half hour at 60 C. While still warm, the solution was filtered to remove the NaCl which was recovered in stoichiometric amounts (0.4 mole). The filtrate was distilled under water pump vacuum to remove the alcohol.

The product was identified as hydroxyethyl-fi-(3,5-di-tbutyl-4-hydroxy benzylthio) propionate.

Analysis.Calcd (percent): C, 65.18; H, 8.75; S, 8.70. Found (percent): C, 65.35; H, 8.91; S, 8.50.

A satisfactory antioxidant should hold the chemical and physical properties of the original organic material during an accelerated oxidation testing procedure, generally up to three hours duration. For the following examples, the test procedure consisted of milling one pound of polyethylene in air on a two-roll laboratory mill having a .4 front roll speed of 25 r.p.m. and a back roll speed of 35 rpm. with the distance between the two rolls adjusted to maintain a uniform rolling back in the nip and a mill temperature of 320 F. After the polymer started to melt, 300 p.p.m. of the antioxidant was added. Samples grams) were taken after 5, 30, 60, 90, and 180 minutes, and melt index, weight percent carbonyl, and oxidation induction time were determined. Oxidation induction time was determined by Differential Thermal Analysis (DTA), indicating the degree of oxidation resistance. The test involves oxidation of the polymer at 392 F. and percent oxygen. The analysis measures the length of time before oxidation startsjThe melt index demonstrates the holding characteristics for the physical properties of the polymer; the carbonyl values, the holding of the chemical properties.

EXAMPLE II Melt Index (M1 Percent of C=O Afte'r Aiter Mill- D'IA, utes 5 30 60 90 180 5 30 60 90 180 Min.

Sample:

*A= Polyethylene+hydroxyethyl-r- (3,5-di-t-butyl-4-hydroxy-b enzylthio) propionate. Y

**B =Polyethylene with no stzbilizer.

wherein m is a positive integer between 2 and 10.

2. Hydroxyethyl B (3,5 di t butyl 4 hydroxybenzylthio) propionate.

References Cited UNITED STATES PATENTS 3,249,632 5/1966 Peterson et a1 260-473 LORRAINE A. WEINBERGER, Primary Examiner E. J. GLEIMAN, Assistant Examiner U.S. Cl. X.R.

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No- 3, 504, 012 Dated March 31 1970 Inventor(s) Harry Braus and Jay R. Woltermann It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Title should read:

HYDROXYALKYL--( 3, 5 -DI-T -BUTYL-4-HYDROXYBENZYLTHIO) PROPIONATE Col. 2, lines 26-30; formula should read C(CH3)3 o H HO CHZ-S-CHZ-CHZ-C-OCHZ-CHZ-OH C(CH3)3 Claim 1: formula should read SIGIQED AND EALEU NOV 2 @1970 Edwardlllletdaqlr. mg, "5.: J3. Aneafin Officer OIIiIBiM o1 Patenta FORM po'mso 10459) USCOMM-DC wan-pus fi II S GCVERN'IEH'I PRINYINCI OFFICE IQ. 0"351'3" 

